Adjustable stage t-type piston device and method using co2 liquid-gas phase change energy

Abstract

The application discloses a T-shaped piston device with adjustable stages utilizing CO2 liquid-gas phase change energy, which comprises a T-shaped piston unit with adjustable stages, a power supply system and a valve controller; the power supply system and the valve controller are connected with the T-shaped piston unit with adjustable stages. The device provides fast, accurate and continuous pressure power for the piston stroke in the limited space of the cylindrical cylinder body, and can accurately show and reflect the relationship between the CO2 mass participating in the liquid-gas phase change and the specific stroke of the piston. The application further discloses a calculation method for converting phase change energy into the adjustable stroke of the T-shaped piston.

Description

Technical Field

[0001] This invention belongs to the field of energy storage equipment technology, specifically relating to an adjustable-stage T-piston device utilizing the energy of CO2 liquid-gas phase change, and a method for calculating the controllable stroke of the adjustable-stage T-piston device utilizing the energy of CO2 liquid-gas phase change. Background Technology

[0002] Currently, most mechanical equipment involving piston stroke motion primarily employs a piston-pushing method relying on hydraulic oil. While this method remains reliable in rapidly evolving equipment and complex field conditions, it suffers from drawbacks for large structures, including high load, high pressure requirements, multiple cylinder stages, and slow speed. The slow speed, in particular, increases the overall motion time by approximately 14% to 33%, severely limiting the overall efficiency and significantly impacting the full utilization of continuous or tiered pushing capabilities. Based on this situation, this paper utilizes the endothermic flash evaporation and rapid expansion characteristics of liquid CO2, using the limited space within a cylindrical cylinder as the phase change space. The phase change pressure is converted into piston kinetic energy, establishing a relationship between the mass of liquid CO2 and the piston stroke. A method for calculating the controllable stroke of an adjustable-stage T-piston device utilizing the phase change energy of CO2 is proposed. Summary of the Invention

[0003] The first objective of this invention is to provide an adjustable-stage T-piston device that utilizes the energy of CO2 liquid-gas phase change to replace the current hydraulic oil medium, providing rapid, precise, and continuous pressure power for the piston stroke within the limited space of a cylindrical cylinder, and accurately representing and reflecting the relationship between the mass of CO2 participating in the liquid-gas phase change and the specific piston stroke.

[0004] The second objective of this invention is to provide a method for calculating the controllable stroke of an adjustable-stage T-piston device that utilizes the phase change energy of CO2 liquid-gas. This method provides a scientific calculation method for the relationship between the mass of liquid CO2 and the phase change energy during this operation and the stroke of the cylinder after the phase change, thus providing theoretical support for the application of technology that utilizes the phase change energy of liquid CO2 for directional release and rapid jacking of large structures.

[0005] The first technical solution adopted in this invention is an adjustable-stage T-piston device utilizing the phase change energy of CO2 liquid-gas, comprising an adjustable-stage T-piston unit, a power supply system, and a valve controller; the power supply system and the valve controller are both connected to the adjustable-stage T-piston unit.

[0006] The invention is further characterized in that:

[0007] The adjustable-stage T-piston unit includes a cylinder body, with a cylinder body base at the first end and a piston assembly at the second end. A safety relief valve and a pressure and temperature monitoring unit are installed on the side wall of the cylinder. It also includes a liquid CO2 filling pipe and an excitation pipe that both pass through the bottom of the cylinder body. The excitation pipe is connected to the power supply system. The end of the liquid CO2 filling pipe located outside the cylinder body is equipped with an electric control pressure regulating valve. The cylinder body is also equipped with an electric regulating ball valve. Both the electric control pressure regulating valve and the electric regulating ball valve are connected to the valve controller.

[0008] The piston assembly includes an interconnected T-shaped piston base and a T-shaped piston column, with the T-shaped piston base located inside the cylinder. The valve body of the electrically adjustable ball valve is located between the T-shaped piston base and the excitation tube. The internal space of the cylinder between the valve body of the electrically adjustable ball valve and the cylinder base forms a phase change space for liquid CO2.

[0009] The pressure and temperature monitoring unit includes a pressure transmitter, a temperature sensor, and a multi-channel data acquisition instrument; the pressure transmitter and temperature sensor are both connected to the data acquisition instrument via an RS485 data acquisition cable. The probes of the pressure transmitter and temperature sensor are both located in the phase change space of liquid CO2 inside the cylinder.

[0010] The second technical solution adopted in this invention is a method for calculating the controllable stroke of an adjustable-stage T-piston device utilizing CO2 liquid-gas phase change energy, comprising the following steps: Step S1: Calculate the energy required for the phase change of liquid CO2 in the phase change space inside the cylinder; Step S2: Calculate the heat received by the liquid CO2 from the excitation tube; Step S3: Based on heat transfer, determine the relationship between the temperature change in the phase change space inside the cylinder and the power of the excitation tube during the phase change of liquid CO2. Step S4: Obtain the mathematical expression for the relationship between pressure change and power in the phase transition space based on the ideal gas law; Step S5: Based on the functional conversion relationship, derive the expression for the T-type piston stroke and its influencing factors.

[0011] The invention is further characterized in that: Step S1 is as follows: The initial temperature of the liquid CO2 in the cylinder before the phase change was determined to be: T 0, the temperature inside the cylinder after phase change is T 1. According to the heat calculation equation, the mass in the cylinder is... m The temperature change of liquid CO2 is Δ T The required energy is E ,but E The constructive formula (1) is shown below: (1) In the formula: EThe energy required for the CO2 phase transition, in J; C ρ is the specific heat capacity of liquid CO2, J / (kg·K).

[0012] Step S2 specifically involves: using electric heating for the excitation tube, and based on the electrical work relationship, from... t 0~ t i The heat generated by the excitation tube within a certain time period As shown in equation (2): (2) In the formula: P 功率 The electrical power of the adjustable-stage high-power, high-thermal-conductivity excitation tube is W; t For time, s; t 0 represents the initial moment, in seconds, when the excitation tube begins to heat up. t i s represents the end time when the excitation tube stops heating.

[0013] Step S3 is as follows: The energy required for the phase change of liquid CO2 in the phase change space of the cylinder is entirely provided by the heat emitted by the excitation tube. Then, by combining equation (1) and equation (2), the relationship between the temperature change in the phase change space and the power of the excitation tube is obtained, as shown in equation (3): (3).

[0014] Step S4 specifically involves: based on the ideal gas law, obtaining the relationship between the pressure change and temperature change of liquid CO2 in the phase transition space, as shown in equation (4): (4) In the formula: Δ P V represents the pressure change of liquid CO2 within the phase change space, in MPa; V is the volume of the phase change space, in m³. 3 ; n The amount of substance of CO2 gas, expressed in mol. m The mass of liquid CO2 inside the tube is expressed in kg. M is the molar mass of CO2 gas, in g / mol; R Δ is the molar gas constant, with a value of 8.314 J / (mol·K); T The temperature change of liquid CO2 within the phase transition space is expressed in K. In equation (3), △ T Substituting the expression into equation (4), we obtain the mathematical expression between the pressure change of liquid CO2 in the phase change space and the power of the excitation tube, as shown in equation (5): (5).

[0015] Step S5 is as follows: According to the formulas for calculating work and force, the pressure formed after the phase change of liquid CO2 in the cylinder is completely converted into kinetic energy, which is manifested as the work done on the piston assembly. The relationship between work and piston stroke is then obtained, as shown in equation (6): (6) Furthermore, since the kinetic energy required for the piston assembly to do work all comes from the heat emitted by the excitation tube, the following equation (7) holds: (7) The mathematical expression for the stroke of the T-type piston is obtained by combining formulas (6) and (7), as shown in formula (8): (8) In addition, the volume of the phase change space inside the cylinder. V The formula for calculating the contact area S between liquid CO2 and the bottom of the T-shaped piston base is shown in equation (9): (9) In equation (9) V and S Substituting the expression into equation (8), the mathematical expression for the stroke L of the T-type piston in the cylindrical cylinder is finally obtained, as shown in equation (10): (10).

[0016] The beneficial effects of this invention are: (1) Based on the physical and chemical properties of liquid CO2’s “endothermic phase change and volume expansion”, the method of the present invention utilizes the mass-energy conversion of a quantitative liquid CO2 after heating to replace the mechanical energy of a conventional oil cylinder. Combined with the law of conservation of energy, by controlling the energy generated by the phase change of liquid CO2, a method for calculating the instantaneous pressure increase controllable energy of liquid CO2 in confined space is established, thereby achieving the purpose of controllable T-type piston stroke. Compared with the currently commonly used mechanical jacking method using hydraulic oil as the medium, it has faster efficiency and lower cost, providing a new idea and approach for the rapid jacking of heavy-duty structures.

[0017] (2) The method of the present invention provides a new way for rapid jacking of large and heavy-duty structures, and provides a scientific calculation method for the relationship between the mass of liquid CO2 and the phase change energy during the jacking process and the stroke of the piston after the phase change. It provides theoretical support for the application practice of the technology of rapidly jacking large structures by directional release of liquid CO2 phase change energy. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the adjustable-stage T-piston device utilizing the phase change energy of CO2 liquid-gas according to the present invention. Figure 2 yes Figure 1 A schematic diagram of the cross section A-A'.

[0019] In the diagram: 1. Power supply system, 2. Power cable, 3. Liquid CO2 filling pipe, 4. Electric control pressure regulating valve, 5. Cylinder base, 6. Excitation tube, 7. Phase change space, 8. Safety relief valve, 9. Multi-channel data acquisition instrument, 10. RS485 data acquisition line, 11. Pressure transmitter, 12. Temperature sensor, 13. Valve control cable, 14. Valve controller, 15. Electric regulating ball valve, 16. T-piston base, 17. T-piston cylinder, 18. Cylinder. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0021] The present invention provides an adjustable-stage T-piston device utilizing the phase change energy of CO2 liquid gas, comprising an adjustable-stage T-piston unit, a power supply system 1, and a valve controller 14; the power supply system 1 and the valve controller 14 are both connected to the adjustable-stage T-piston unit.

[0022] The adjustable T-type piston unit includes a cylinder body 18, with a cylinder body base 5 at the first end and a piston assembly at the second end. A safety relief valve 8 and a pressure and temperature monitoring unit are installed on the side wall of the cylinder 18; It also includes a liquid CO2 filling pipe 3 and an excitation pipe 6, both of which pass through the cylinder base 5. The excitation pipe 6 is connected to the power supply system 1 via a power supply cable 2. The first ends of the liquid CO2 filling pipe 3 and the excitation pipe 6 are located outside the cylinder 18, and the second ends of the liquid CO2 filling pipe 3 and the excitation pipe 6 are located inside the cylinder 18. An electric control pressure regulating valve 4 is provided at the end of the liquid CO2 filling pipe 3 located outside the cylinder 18. An electric regulating ball valve 15 is also installed on the cylinder 18. The electric control pressure regulating valve 4 and the electric regulating ball valve 15 are both connected to the valve controller 14 via a valve control cable 13.

[0023] The piston assembly includes a T-shaped piston base 16 and a T-shaped piston column 17 that are connected to each other. The T-shaped piston base 16 is located inside the cylinder body 18. The valve body of the electrically adjustable ball valve 15 is located between the T-shaped piston base 16 and the excitation tube 6. The internal space of the cylinder body 18 between the valve body of the electrically adjustable ball valve 15 and the cylinder base 5 forms a phase change space 7 for liquid CO2.

[0024] The pressure and temperature monitoring unit includes a pressure transmitter 11, a temperature sensor 12, and a multi-channel data acquisition instrument 9; the pressure transmitter 11 and the temperature sensor 12 are both connected to the data acquisition instrument 9 via an RS485 data acquisition cable 10. The probes of the pressure transmitter 11 and the temperature sensor 12 are both located in the phase change space 7 of liquid CO2 inside the cylinder 18.

[0025] Among them, the power supply system 1 is a 3ST series three-phase adjustable step-up transformer; the electric control pressure regulating valve 4 is model ZAZN or ZAZP; the multi-channel data acquisition instrument 9 is model LianCe-SIN-R5000C; the pressure transmitter 11 is model SIN-P310; the temperature sensor 12 is model PT100; the valve controller 14 is model BFA-3; and the electric regulating ball valve 15 is model Q941F. This invention also provides a method for calculating the controllable stroke of an adjustable-stage T-piston device utilizing the phase change energy of CO2 liquid-gas, comprising the following steps: Step S1: Calculate the energy required for the phase change of liquid CO2 in the phase change space 7 inside the cylinder 18; Step S1 is as follows: The initial temperature of the liquid CO2 in cylinder 18 before the phase change was determined to be: T 0, the temperature inside cylinder 18 after phase change is T 1. According to the heat calculation equation, the mass in cylinder 18 is... m The temperature change of liquid CO2 is Δ T ( T 0→ T 1) The required energy is E ,but E The constructive formula (1) is shown below: (1) In the formula: E The energy required for the CO2 phase transition, in J; C ρ is the specific heat capacity of liquid CO2, J / (kg·K).

[0026] Step S2: Calculate the heat received by the liquid CO2 from the excitation tube 6; Step S2 specifically involves: The excitation tube 6 is electrically heated; based on the electrical work relationship, from... t 0~ t i Within a given time period, the heat generated by excitation tube 6 As shown in equation (2): (2) In the formula: P 功率 The electrical power of the adjustable-stage high-power, high-thermal-conductivity excitation tube is W; t For time, s; t 0 represents the initial moment, in seconds, when excitation tube 6 begins heating; t i The time s is the end time when the excitation tube 6 stops heating.

[0027] Step S3: Based on the heat transfer, determine the relationship between the temperature change in the phase change space 7 inside the cylinder 18 and the power of the excitation tube 6 during the liquid CO2 phase change process. Step S3 is as follows: The energy required for the phase change of liquid CO2 in the phase change space 7 of cylinder 18 is entirely provided by the heat emitted by the excitation tube 6. Then, by combining Equation 1 and Equation 2, the relationship between the temperature change in the phase change space and the power of the excitation tube is obtained, as shown in Equation (3): (3).

[0028] Step S4: Obtain the mathematical expression for the relationship between pressure change and power within the phase change space 7 based on the ideal gas law; Step S4 specifically involves: the initial test filling temperature of the liquid CO2 in cylinder 18 is -30℃, the injection pressure is 1.4MPa, and the density is 1101kg / m³. 3 Under these temperature and pressure conditions, the volume of liquid CO2 increases to 562 times its original volume after vaporization. According to the ideal gas law, the relationship between the pressure change and temperature change of liquid CO2 in phase change space 7 is obtained, as shown in equation (4): (4) In the formula: Δ P V represents the pressure change of liquid CO2 within the phase change space, in MPa; V is the volume of the phase change space, in m³. 3 ; n The amount of substance of CO2 gas, expressed in mol. m The mass of liquid CO2 inside the tube is expressed in kg. M is the molar mass of CO2 gas, in g / mol; R Δ is the molar gas constant, with a value of 8.314 J / (mol·K); T The temperature change of liquid CO2 within the phase transition space is expressed in K. In equation (3), △ T Substituting the expression into equation (4), we obtain the mathematical expression between the pressure change of liquid CO2 in the phase change space (7) and the power of the excitation tube (6), as shown in equation (5): (5).

[0029] Step S5: Based on the functional conversion relationship, derive the expression for the T-type piston stroke and its influencing factors.

[0030] Step S5 is as follows: According to the formula for calculating work and force, the pressure formed after the phase change of liquid CO2 in cylinder 18 is completely converted into kinetic energy, which is manifested as the work done on the piston assembly. The relationship between work and piston stroke is then obtained, as shown in equation (6): (6) Furthermore, since the kinetic energy required for the piston assembly to do work is entirely derived from the heat emitted by the excitation tube 6, the following equation (7) holds: (7) The mathematical expression for the stroke of the T-type piston is obtained by combining formulas (6) and (7), as shown in formula (8): (8) In addition, the volume of the phase change space 7 inside the cylinder block 18 V The formula for calculating the contact area S between liquid CO2 and the bottom of the T-type piston base 16 is shown in equation (9): (9) In equation (9) V and S Substituting the expression into equation (8), the mathematical expression for the stroke L of the T-type piston in the cylindrical cylinder is finally obtained, as shown in equation (10): (10) From equation (10), it can be seen that the stroke of the T-type piston after the liquid CO2 phase change in the cylindrical cylinder is affected by the mass of the liquid CO2 phase change in the cylinder 18. m The temperature difference between the liquid CO2 inside cylinder 18 before and after the phase change ( ) T 1- T 0), Length of the phase change space in the cylindrical cylinder block ( l ), power of excitation tube 6 () P 功率 ) and the duration of fever ( t 1- t 0) The influence of parameters, among which the mass of liquid CO2, temperature difference, power and heating time are the key factors affecting the stroke of the T-type piston.

[0031] Example 1 An adjustable-stage T-piston device utilizing the phase change energy of CO2 liquid-gas includes an adjustable-stage T-piston unit, a power supply system 1, and a valve controller 14; both the power supply system 1 and the valve controller 14 are connected to the adjustable-stage T-piston unit.

[0032] Example 2 An adjustable-stage T-piston device utilizing the phase change energy of CO2 liquid-gas includes an adjustable-stage T-piston unit, a power supply system 1, and a valve controller 14; both the power supply system 1 and the valve controller 14 are connected to the adjustable-stage T-piston unit.

[0033] The adjustable T-type piston unit includes a cylinder body 18, with a cylinder body base 5 at the first end and a piston assembly at the second end. A safety relief valve 8 and a pressure and temperature monitoring unit are installed on the side wall of the cylinder 18; It also includes a liquid CO2 filling pipe 3 and an excitation pipe 6, both of which pass through the cylinder base 5. The excitation pipe 6 is connected to the power supply system 1 via a power supply cable 2. The first ends of the liquid CO2 filling pipe 3 and the excitation pipe 6 are located outside the cylinder 18, and the second ends of the liquid CO2 filling pipe 3 and the excitation pipe 6 are located inside the cylinder 18. An electric control pressure regulating valve 4 is provided at the end of the liquid CO2 filling pipe 3 located outside the cylinder 18. An electric regulating ball valve 15 is also installed on the cylinder 18. The electric control pressure regulating valve 4 and the electric regulating ball valve 15 are both connected to the valve controller 14 via a valve control cable 13.

[0034] Example 3 An adjustable-stage T-piston device utilizing the phase change energy of CO2 liquid-gas includes an adjustable-stage T-piston unit, a power supply system 1, and a valve controller 14; both the power supply system 1 and the valve controller 14 are connected to the adjustable-stage T-piston unit.

[0035] The adjustable T-type piston unit includes a cylinder body 18, with a cylinder body base 5 at the first end and a piston assembly at the second end. A safety relief valve 8 and a pressure and temperature monitoring unit are installed on the side wall of the cylinder 18; It also includes a liquid CO2 filling pipe 3 and an excitation pipe 6, both of which pass through the cylinder base 5. The excitation pipe 6 is connected to the power supply system 1 via a power supply cable 2. The first ends of the liquid CO2 filling pipe 3 and the excitation pipe 6 are located outside the cylinder 18, and the second ends of the liquid CO2 filling pipe 3 and the excitation pipe 6 are located inside the cylinder 18. An electric control pressure regulating valve 4 is provided at the end of the liquid CO2 filling pipe 3 located outside the cylinder 18. An electric regulating ball valve 15 is also installed on the cylinder 18. The electric control pressure regulating valve 4 and the electric regulating ball valve 15 are both connected to the valve controller 14 via a valve control cable 13.

[0036] The piston assembly includes a T-shaped piston base 16 and a T-shaped piston column 17 that are connected to each other. The T-shaped piston base 16 is located inside the cylinder body 18. The valve body of the electrically adjustable ball valve 15 is located between the T-shaped piston base 16 and the excitation tube 6. The internal space of the cylinder body 18 between the valve body of the electrically adjustable ball valve 15 and the cylinder base 5 forms a phase change space 7 for liquid CO2.

[0037] Example 4 An adjustable-stage T-piston device utilizing the phase change energy of CO2 liquid-gas includes an adjustable-stage T-piston unit, a power supply system 1, and a valve controller 14; both the power supply system 1 and the valve controller 14 are connected to the adjustable-stage T-piston unit.

[0038] The adjustable T-type piston unit includes a cylinder body 18, with a cylinder body base 5 at the first end and a piston assembly at the second end. A safety relief valve 8 and a pressure and temperature monitoring unit are installed on the side wall of the cylinder 18; It also includes a liquid CO2 filling pipe 3 and an excitation pipe 6, both of which pass through the cylinder base 5. The excitation pipe 6 is connected to the power supply system 1 via a power supply cable 2. The first ends of the liquid CO2 filling pipe 3 and the excitation pipe 6 are located outside the cylinder 18, and the second ends of the liquid CO2 filling pipe 3 and the excitation pipe 6 are located inside the cylinder 18. An electric control pressure regulating valve 4 is provided at the end of the liquid CO2 filling pipe 3 located outside the cylinder 18. An electric regulating ball valve 15 is also installed on the cylinder 18. The electric control pressure regulating valve 4 and the electric regulating ball valve 15 are both connected to the valve controller 14 via a valve control cable 13.

[0039] The piston assembly includes a T-shaped piston base 16 and a T-shaped piston column 17 that are connected to each other. The T-shaped piston base 16 is located inside the cylinder body 18. The valve body of the electrically adjustable ball valve 15 is located between the T-shaped piston base 16 and the excitation tube 6. The internal space of the cylinder body 18 between the valve body of the electrically adjustable ball valve 15 and the cylinder base 5 forms a phase change space 7 for liquid CO2.

[0040] The pressure and temperature monitoring unit includes a pressure transmitter 11, a temperature sensor 12, and a multi-channel data acquisition instrument 9; the pressure transmitter 11 and the temperature sensor 12 are both connected to the data acquisition instrument 9 via an RS485 data acquisition cable 10. The probes of the pressure transmitter 11 and the temperature sensor 12 are both located in the phase change space 7 of liquid CO2 inside the cylinder 18.

[0041] Example 5 The method for calculating the controllable stroke of an adjustable-stage T-piston device utilizing the phase change energy of CO2 liquid-gas includes the following steps: Step S1: Calculate the energy required for the phase change of liquid CO2 in the phase change space 7 inside the cylinder 18; Step S2: Calculate the heat received by the liquid CO2 from the excitation tube 6; Step S3: Based on the heat transfer, determine the relationship between the temperature change in the phase change space 7 inside the cylinder 18 and the power of the excitation tube 6 during the liquid CO2 phase change process. Step S4: Obtain the mathematical expression for the relationship between pressure change and power within the phase change space 7 based on the ideal gas law; Step S5: Based on the functional conversion relationship, derive the expression for the T-type piston stroke and its influencing factors.

[0042] Example 6 The method for calculating the controllable stroke of an adjustable-stage T-piston device utilizing the phase change energy of CO2 liquid-gas includes the following steps: Step S1: Calculate the energy required for the phase change of liquid CO2 in the phase change space 7 inside the cylinder 18; Step S1 is as follows: The initial temperature of the liquid CO2 in cylinder 18 before the phase change was determined to be: T 0, the temperature inside cylinder 18 after phase change is T 1. According to the heat calculation equation, the mass in cylinder (18) is m The temperature change of liquid CO2 is Δ T The required energy is E ,but E The constructive formula (1) is shown below: (1) In the formula: E The energy required for the CO2 phase transition, in J; C ρ is the specific heat capacity of liquid CO2, J / (kg·K).

[0043] Step S2: Calculate the heat received by the liquid CO2 from the excitation tube 6; Step S3: Based on the heat transfer, determine the relationship between the temperature change in the phase change space 7 inside the cylinder 18 and the power of the excitation tube 6 during the liquid CO2 phase change process. Step S4: Obtain the mathematical expression for the relationship between pressure change and power within the phase change space 7 based on the ideal gas law; Step S5: Based on the functional conversion relationship, derive the expression for the T-type piston stroke and its influencing factors.

Claims

1. An adjustable-stage T-piston device utilizing the energy of CO2 liquid-gas phase change, characterized in that, It includes an adjustable T-type piston unit, a power supply system (1) and a valve controller (14); the power supply system (1) and the valve controller (14) are both connected to the adjustable T-type piston unit.

2. The adjustable-stage T-piston device utilizing CO2 liquid-gas phase change energy according to claim 1, characterized in that, The adjustable T-type piston unit includes a cylinder body (18), with a cylinder body base (5) at the first end and a piston assembly at the second end; A safety relief valve (8) and a pressure and temperature monitoring unit are installed on the side wall of the cylinder (18); It also includes a liquid CO2 filling pipe (3) and an excitation pipe (6) that both pass through the cylinder base (5). The excitation pipe (6) is connected to the power supply system (1). The end of the liquid CO2 filling pipe (3) located outside the cylinder (18) is provided with an electric control pressure regulating valve (4). The cylinder (18) is also provided with an electric regulating ball valve (15). The electric control pressure regulating valve (4) and the electric regulating ball valve (15) are both connected to the valve controller (14).

3. The adjustable-stage T-piston device utilizing CO2 liquid-gas phase change energy according to claim 2, characterized in that, The piston assembly includes a T-shaped piston base (16) and a T-shaped piston column (17) connected to each other. The T-shaped piston base (16) is located inside the cylinder (18). The valve body of the electric regulating ball valve (15) is located between the T-shaped piston base (16) and the excitation tube (6). The internal space of the cylinder (18) between the valve body of the electric regulating ball valve (15) and the cylinder base (5) forms a phase change space (7) for liquid CO2.

4. The adjustable-stage T-piston device utilizing CO2 liquid-gas phase change energy according to claim 3, characterized in that, The pressure and temperature monitoring unit includes a pressure transmitter (11), a temperature sensor (12), and a multi-channel data acquisition instrument (9); the pressure transmitter (11) and the temperature sensor (12) are both connected to the data acquisition instrument (9) via an RS485 data acquisition line (10); The probes of the pressure transmitter (11) and the temperature sensor (12) are both located in the phase change space (7) of liquid CO2 inside the cylinder (18).

5. A method for calculating the controllable stroke of an adjustable-stage T-piston device utilizing the phase change energy of CO2 liquid-gas, characterized in that... Includes the following steps: Step S1: Calculate the energy required for the phase change of liquid CO2 in the phase change space (7) inside the cylinder (18); Step S2: Calculate the heat generated by the liquid CO2 received by the excitation tube (6); Step S3: Based on the heat transfer, determine the relationship between the temperature change in the phase change space (7) inside the cylinder (18) and the power of the excitation tube (6) during the liquid CO2 phase change process; Step S4: Obtain the mathematical expression between pressure change and power in the phase transition space (7) based on the ideal gas law; Step S5: Based on the functional conversion relationship, derive the expression for the T-type piston stroke and its influencing factors.

6. The method for calculating the controllable stroke of the adjustable-stage T-piston device utilizing CO2 liquid-gas phase change energy according to claim 5, characterized in that, Step S1 is as follows: The initial temperature of the liquid CO2 in the cylinder (18) before the phase change was determined to be: T 0, the temperature inside the cylinder (18) after phase change is T 1. According to the heat calculation equation, the mass in cylinder (18) is m The temperature change of liquid CO2 is Δ T The required energy is E ,but E The constructive formula (1) is shown below: （1） In the formula: E The energy required for the CO2 phase transition, in J; C ρ is the specific heat capacity of liquid CO2, J / (kg·K).

7. The method for calculating the controllable stroke of the adjustable-stage T-piston device utilizing CO2 liquid-gas phase change energy according to claim 6, characterized in that, Step S2 specifically involves: the excitation tube (6) is electrically heated, and according to the electrical work relationship, from... t 0~ t i The heat generated by the excitation tube (6) within a certain time period As shown in equation (2): （2） In the formula: P 功率 The electrical power of the adjustable-stage high-power, high-thermal-conductivity excitation tube is W; t For time, s; t 0 represents the initial heating time of the excitation tube (6), in seconds; t i The time s is the end time when the excitation tube (6) stops heating.

8. The method for calculating the controllable stroke of the adjustable-stage T-piston device utilizing CO2 liquid-gas phase change energy according to claim 7, characterized in that, Step S3 is as follows: The energy required for the phase change of liquid CO2 in the phase change space (7) of the cylinder (18) is entirely provided by the heat emitted by the excitation tube (6). Then, by combining equation (1) and equation (2), the relationship between the temperature change in the phase change space and the power of the excitation tube is obtained, as shown in equation (3): （3）。 9. The method for calculating the controllable stroke of the adjustable-stage T-piston device utilizing CO2 liquid-gas phase change energy according to claim 8, characterized in that, Step S4 specifically involves: based on the ideal gas law, obtaining the relationship between the pressure change and temperature change of liquid CO2 within the phase transition space (7), as shown in equation (4): （4） In the formula: Δ P V represents the pressure change of liquid CO2 within the phase change space, in MPa; V is the volume of the phase change space, in m³. 3 ; n The amount of substance of CO2 gas, expressed in mol. m The mass of liquid CO2 inside the tube is expressed in kg. M ρ represents the molar mass of CO2 gas, in g / mol; R Δ is the molar gas constant, with a value of 8.314 J / (mol·K); T The temperature change of liquid CO2 within the phase transition space is expressed in K. In equation (3), △ T Substituting the expression into equation (4), we obtain the mathematical expression between the pressure change of liquid CO2 in the phase change space (7) and the power of the excitation tube (6), as shown in equation (5): （5）。 10. The method for calculating the controllable stroke of the adjustable-stage T-piston device utilizing CO2 liquid-gas phase change energy according to claim 9, characterized in that, Step S5 is as follows: According to the formula for calculating work and force, the pressure formed after the liquid CO2 phase change in the cylinder (18) is completely converted into kinetic energy, which is manifested as the work done on the piston assembly. The relationship between work and piston stroke is then obtained, as shown in formula (6): （6） Furthermore, since the kinetic energy required for the piston assembly to do work is entirely derived from the heat emitted by the excitation tube (6), the following equation (7) holds: （7） The mathematical expression for the stroke of the T-type piston is obtained by combining formulas (6) and (7), as shown in formula (8): （8） In addition, the volume of the phase change space (7) inside the cylinder (18) V The formula for calculating the contact area S between liquid CO2 and the bottom of the T-shaped piston base (16) is shown in equation (9): （9） In equation (9) V and S Substituting the expression into equation (8), the mathematical expression for the stroke L of the T-piston in the cylindrical cylinder is finally obtained, as shown in equation (10): （10）。

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